In a printing system, accurate and reliable registration of the substrate media as it is transferred in a process direction is desirable. Even a slight skew or misalignment of the substrate media through an image transfer zone can lead to image and/or color registration errors. For example, in printing systems transporting substrate media using nip assemblies or belts, slight skew of the substrate media can cause processing errors. Also, as substrate media is transferred between sections of the printing system, the amount of skew can increase or accumulate. In modular overprint systems, the accumulation of skew will translate into substrate media positioning errors between module exit and entry points, particularly in a cross-process direction. Such errors can cause large push, pull or shearing forces to be generated, which transmit to the substrate media being transported. Medium and light-weight substrate media cannot generally support large forces, which will cause wrinkling, buckling or tearing of such media.
One method for registering and aligning a sheet is the use of stalled rolls. In the stalled roller technique, a sheet is driven into a nip in which the rollers are stopped causing a buckle to be formed between the stalled roller and the driving rollers. The force on the media which creates the buckle also causes the lead edge of the sheet to align itself within the stalled nip and the stalled nip is then activated so that the sheet is forwarded in the proper aligned position. However, often the leading edge of the media will penetrate the nip and remain skewed. This is especially the case for media having a high degree of rigidity, such as cardstock.
Accordingly, it would be desirable to provide an apparatus, method and system of registering and de-skewing a substrate media, which overcomes the shortcoming of the prior art.